In U.S. Pat. No. 3,721,756, a system is disclosed for producing a display on a screen wherein a multi-track magnetic storage drum is employed for storage of information to be displayed. A multi-faceted mirror scanner is mounted for rotation in predetermined relation with respect to the magnetic storage drum by mounting the mirror and the drum on a common drive shaft. A plurality of sources produce light beams which are incident on the mirror scanner in a selected pattern and reflected thereby to sweep a display screen. Electrically driven light modulators, preferably of the acousto-optic type, individually amplitude modulate the light beams in accordance with information read from the drum by magnetic read/write heads disposed adjacent the periphery of the drum.
Due to the mirror scanner and the storage drum being mounted on a common shaft, the described system eliminates the need for servo synchronization between the mirror scanner drive and the drum drive. Furthermore, the described system reduces the data buffering requirements from those determined largely by servo errors to much smaller ones determined by drum location and facet angle errors of the mirror scanner.
Although the described system reduces servo synchronization and data buffer requirements, it is still a complex system since it requires, in addition to the magnetic storage drum, the mirror scanner, and the light sources, a bank of read/write heads and a plurality of light amplitude modulators. A substantially simplified display system would result if the functions of the read/write heads and light amplitude modulators could be assumed by the data storage component of the system.